Equilibrium surface segregation enthalpy of Ge in concentrated amorphous SiGe alloys

Abstract Auger electron spectroscopy technique was used to study surface segregation of Ge in concentrated amorphous Si 1- x Ge x thin film alloys. The alloys (with Ge bulk concentrations in the range of 18–58 at.%) were prepared by dc magnetron sputtering and annealed in a UHV chamber in the temperature range of 653–673 K. The surface equilibrium data ( X s(Ge) versus X b(Ge) ) were determined from segregation kinetics. We show that (i) the experimental data can be interpreted using McLean–Langmuir isotherms with a segregation enthalpy Δ H (exp) equals to 5.3±0.5 kJ mol −1 and (ii) the estimated segregation enthalpy is lower than the theoretical one calculated in crystalline alloys neglecting the alloying and the size effects.